Personal watercraft engine fluid cooling system

ABSTRACT

An engine fluid cooling system that utilizes the jet propulsion unit of a personal watercraft to cool the engine fluid. The cooling system includes passages for transporting engine fluid to and from a cooling system that includes a cooling channel formed about a component of the jet propulsion unit so that as the engine fluid travels through the cooling channel, heat, contained in the engine fluid, is transferred to the water flowing through the jet propulsion unit.

FIELD

This disclosure relates to a system for cooling engine fluids in apersonal watercraft. More particularly, this disclosure relates to acooling system utilizing the watercraft's jet propulsion unit to coolengine fluids.

BACKGROUND

Personal watercrafts have an internal combustion engine contained withinan engine compartment that is typically positioned forward of thetunnel. The engine powers a jet propulsion unit that propels thewatercraft through the water. The output shaft of the engine drives animpeller on the jet propulsion unit. The impeller, which isconventionally contained within a housing, pulls in water from a waterinlet located on the underside of the boat, and discharges the water athigh velocity through a steerable nozzle at the rear of the boat. An oiltank, typically provided adjacent to or within the engine contains alubricating fluid for lubricating the moving parts of the engine. Thelubricating fluid, typically oil, is cycled through the engine andreturns to the oil tank where it is reused until the lubricating fluidis drained and replaced during routine maintenance.

During operation, the lubricating fluid absorbs heat and must be cooledto function effectively. Known systems for cooling oil involve pumpingoil from the engine to a tubular member located proximate to the waterinlet. The water drawn up the water inlet by the jet propulsion pumppasses over the tubular member and cools the engine oil containedtherein. Other systems employ heat exchangers mounted to the internalcombustion engine that draw heat from the lubricating oil and absorb itinto a cooling fluid.

Engine fluids can be efficiently cooled by utilizing the flow of coolwater through the jet propulsion unit.

SUMMARY

In various embodiments there is provided a personal watercraft thatincludes a hull and an overlying deck that includes a cavity defining anengine compartment. The watercraft further includes an engine located inthe engine compartment, coupled to a jet propulsion unit for poweringthe watercraft. A cooling system for cooling a lubricating fluid of theengine is also included. The cooling system includes a lubricating fluidchannel surrounding a component of the jet propulsion unit for flowingthe lubricating liquid through the liquid passage to exchange heat ofthe lubricating fluid with water taken up by the jet propulsion unit.

In various embodiments there is provided a cooling system for enginelubricating fluid for a jet-propelled watercraft. The cooling systemincludes a jet propulsion unit and a channel formed about a component ofthe jet propulsion unit for circulating engine lubricating fluidthereabout. The cooling system further includes a fluid passagewaycoupled to an engine lubricating fluid reservoir for delivering heatedlubricating fluid to the channel where it is cooled and then returningthe lubricating fluid to the reservoir.

In various embodiments there is provided a jet propulsion unit for ajet-propelled watercraft. The jet propulsion unit includes an outerhousing, an impeller journalled within the outer housing, a dischargenozzle positioned rearward of the impeller, and an engine lubricatingfluid channel formed about an exterior of the outer housing so that heatfrom the engine lubricating fluid is transferred to water pumped by thejet pump.

DRAWINGS

FIG. 1 is a perspective view of a typical personal watercraft with theengine fluid cooling system.

FIG. 2 is a perspective exploded view of a prior art jet propulsion unitfrom a typical personal watercraft.

FIG. 3 is a schematic of an embodiment of an engine fluid coolingsystem.

FIG. 4 is a perspective view of an embodiment of an engine fluid coolingsystem shown coupled to a personal watercraft engine.

FIG. 5 is a perspective view of an embodiment of an engine fluid coolingsystem shown coupled to a personal watercraft engine.

FIG. 6 is a perspective view of an embodiment of an engine fluid coolingsystem provided on a jet pump housing of a jet propulsion unit.

FIG. 7 is a front perspective view of an embodiment of an engine fluidcooling system shown provided on a jet pump housing of a jet propulsion.

FIG. 8 is flowchart illustrating the operation of an embodiment of anengine fluid cooling system.

DESCRIPTION OF VARIOUS EMBODIMENTS

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are numberedidentically. The drawings, which are not necessarily drawn to scale,depict selected embodiments and are not intended to limit the scope ofthe embodiments. Several forms of the embodiments will be shown anddescribed, and other forms will be apparent to those skilled in the art.It will be understood that embodiments shown in drawings and describedare merely for illustrative purposes and are not intended to limit thescope of the embodiments as defined in the claims that follow. Althoughthe engine fluid cooling system is shown with respect to a sit-down typejet ski it should be understood that the embodiments of the engine fluidcooling system can be practiced with any marine vehicle that utilizes ajet propulsion unit.

FIG. 1 illustrates generally a watercraft 10 that can include theembodiments of the engine fluid cooling system, as will be describedhereinafter. Watercraft 10 has generally a front or bow 12 and a rear orstern 14 and includes an upper portion 16 that includes a top deck 18and shroud 20. The top deck 18 is secured to a bottom hull 22 along anoverlapping portion covered with a rub rail 24, thereby forming a hull.The hull formed by the bottom hull 22 and top deck 18 defines acompartment sized to house an internal combustion engine 28 for poweringthe watercraft 10 and may also include one or more storage compartments(not shown), depending on the size and configuration of the watercraft.

The deck portion 18 also has a raised, longitudinally extending seat 30adapted to accommodate one or more riders seated in straddle fashion. Agrab handle 31 may be disposed transversely across the rear of the seat30.

Engine 28 powers a jet propulsion unit 32 (described with more detailwith respect to FIG. 2), typically mounted in a tunnel at the bottomrear portion of the watercraft, all shown in phantom in FIG. 1. An oilreservoir 33 is provided adjacent to the engine for providinglubrication to the moving parts of the engine. Jet propulsion unit 32includes a steerable water discharge nozzle 34 that is operativelycoupled to a set of handlebars 36 to facilitate steering of thewatercraft by the operator. The connection between handlebars 36 anddischarge nozzle 34 may be of any suitable type, and typically includesmechanical linkages including a control cable (not shown). If desired,an electronic connection could also be utilized.

The engine may be a two-stroke or four-stroke type engine. Typically, infour-stroke engine watercrafts, a cooling system that circulates acooling fluid, typically, a glycol/water mixture, is employed. Closedloop cooling systems, (not shown) are well known in the art and includegenerally, a coolant reservoir, which includes inlet and outlet conduitsfor directing coolant to and from the engine. Typically, a pump isincluded for continually circulating the fluid. In operation, as theengine cycles, coolant is circulated through various components of theengine where heat from the engine is transferred to the coolant.Thereafter, the coolant is returned to the coolant reservoir.

FIG. 2 is an exploded perspective view of a typical prior art jetpropulsion unit 40 for a personal watercraft. Jet propulsion unit 40 isusually positioned towards the rear of the watercraft near a waterinlet. A water inlet is generally provided at the rear of thewatercraft. The jet propulsion unit 40 typically includes a water jethousing 42, a pump stator 44 and impeller 48. The pump stator 44includes a plurality of stator blades 46 and impeller 48 includes aplurality of blades 50. Jet propulsion unit 40 may also include a pumpextension 52 and a first stationary nozzle 54 and second rotatablenozzle 56. The impeller 48 is coupled to the engine (shown in FIG. 1)via a drive shaft (shown in FIG. 4) to pull water from the body of waterin which the watercraft is operated.

The moving parts of 4-stroke engines are typically lubricated with oil.In the course of lubrication, heat generated by the moving parts of theengine is transferred to the lubricating fluid as it circulates,undesirably increasing the temperature of the lubricating fluid, which,in turn, decreases its efficiency as a lubricant. Obviously, the heatabsorbed by the lubricating fluid must be transferred to another sourceto maintain functionality of the lubricating fluid, as well as, so thatthe lubricating fluid has capacity to absorb more heat on its subsequentpass through the engine.

FIG. 3 illustrates, diagrammatically, the cooling system of thedisclosure. Typically, engines include a closed loop system 57 forcirculating engine fluids, including, without limitation, enginelubricant and engine coolant. The closed loop system 57 continuallyrecycles a volume of fluid until the fluid is replaced. Generally,engine fluids absorb heat produced by the moving parts of the engine sothat the engine can operate efficiently. In order for the engine fluidsto function efficiently, heat absorbed by the engine fluids must beremoved. An embodiment of the engine fluid cooling system includes anopen loop cooling system 59 that works in cooperation with the closedloop system 57 to remove heat retained in the engine fluid circulatingtherein. In operation, a heat transfer, depicted at 61, occurs betweenthe closed loop system 57 and the open loop system 59.

FIG. 4 depicts an embodiment of the engine lubricating fluid coolingsystem. FIG. 4 illustrates a typical 4-stroke engine 58 for a personalwatercraft coupled to a typical jet propulsion unit 40 via a drive shaft60 for driving the impeller (shown in FIG. 2). The engine 58 includes anoil reservoir 33 for holding oil after it circulates through variousparts of the engine 58. Oil passage lines 64 and 66 are coupled toopenings (not shown) in the oil reservoir 33. The oil passage lines 64and 66 may be made of rubber, plastic, metal, or any other suitablematerial. Oil passage line 64 transports warmed engine oil to the jetpropulsion unit 40, where it is cooled. Return line 66 extends from acooling channel 68 of the jet propulsion unit 40 to the reservoir 33 forreturning cooled oil to the reservoir 33 so that it may circulatethrough the engine 58.

In the embodiment depicted in FIG. 4, the engine fluid being cooled isengine lubricating oil. Oil passage line 64 is coupled to a channel 68,which is a hollow conduit 70 that is coiled about a component of the jetpropulsion unit 40. The conduit 70 is shown coiled about the jet pumphousing of the jet propulsion unit 40. The conduit 70 is made of amaterial that allows for heat transfer, such as, without limitation,plastic, rubber, or metal. The diameter of the conduit 70 will varydepending upon the geometry of the component on which it is installed.It is preferable to maximize the surface area over which heat transferwill occur. Therefore, the diameter and geometry of the conduit 70 maybe varied so that efficient cooling can occur.

The conduit 70 is coupled to the oil passage line 64 for deliveringheated oil to the channel 68 and oil return line 66 for returning cooledoil to the reservoir 33. As the heated oil travels the length of theconduit, heat contained in the oil is transferred to the cool waterstreaming through the jet propulsion unit 40. Typically, as is known inthe art, in closed loop systems, the system is pressurized and a smallpump may be provided to continuously circulate the oil between thereservoir, engine and cooling system.

FIG. 5 illustrates an alternate embodiment where engine fluid, forexample, engine coolant, is circulated to the cooling system at the jetpropulsion unit 40. Similar to the embodiment depicted in FIG. 4, anoutlet 66 and inlet 64 line are coupled to the engine coolant reservoir69 and the cooling system is provided at the jet propulsion unit 40.This embodiment operates similarly to the embodiment depicted in FIG. 4.Typically, in closed loop systems, a pump is provided to maintainconstant circulation. In general, the pressure created by this pump isadequate to continue the flow of coolant throughout the engine and toand from the open loop cooling system 59 provided at the jet propulsionunit 40. Thus, after coolant has circulated through the engine andabsorbed heat therefrom, it circulates to the cooling system and theheat is transferred to the ambient water flowing through the jetpropulsion unit 40.

FIG. 6 is a more detailed perspective view of an embodiment of thecooling channel. As can be seen, a length of hollow conduit 70 is coileda number of times about the exterior of the jet propulsion unit 40. Inthe embodiment depicted, the hollow conduit 70 is coiled about theexterior surface of the jet pump housing 72 in a linear fashion. Thoseskilled in the art will appreciate that the conduit may be coiled aboutthe component in any pattern, such as, for example, a helical pattern.In the embodiment depicted in FIG. 4, the adjacent coils are showntouching each other. The coils may or may not be welded together,however, it should be understood that the conduit may be coiled suchthat a gap is left between adjacent coils. The number of times that theconduit is coiled about a component is dependent on factors such as thelength and diameter of the conduit as well as the geometry of theparticular jet propulsion component about which the conduit is coiled.As mentioned above, it is desirable to maximize the surface area tomaximize heat transfer.

As water is drawn through the jet pump housing 72, heat from the oilflowing through the hollow conduit 70 is transferred to the water thatis at a lower temperature and thus cools the oil. The engine fluidcooling system de allows for cooling at any engine speed including idle.In a typical watercraft, the impeller rotates at approximately 1,500 RPMat idle. Thus, water continues to travel through the jet pump systemeven when the watercraft is at idle, thus providing continuous coolingcapacity of engine fluids even when the watercraft is not in motion.

FIG. 7 depicts an embodiment of a cooling channel. In this embodiment,the oil is directed from the engine to a cooling channel 68 that isformed between the outer surface 74 of a component of the jet propulsionunit 40 and an internal surface 76 of ajacket 78. The jacket 78 iscomprised of a solid enclosure that encases any qualifying component ofthe jet propulsion unit (described above). In the embodiment depicted inFIG. 7, the channel 68 is shown formed on the jet pump housing 79. Anempty space, or channel 80 is created between the jet propulsion unitcomponent and the jacket through which heated oil delivered from the oilreservoir may flow and transfer heat to the water traveling through thejet propulsion unit 40. Alternately, the cooling channel jacket 78 maybe formed of a single piece that includes an internal channel with wallsdefined solely by the internal surfaces of the jacket. In thisembodiment, the oil does not directly contact a surface of the jetpropulsion unit. However, an internal surface contacts the outer surfaceof the jet propulsion unit and heat transfer from the oil to the waterflowing through the jet propulsion unit occurs through the surface ofthe jacket and the surface of the jet propulsion unit. The jacket may befabricated from metal, plastic, rubber, or any other suitable materialthat is impermeable yet capable of transferring heat efficiently. Aseparate water jacket piece as described above may be used to retrofitan existing jet propulsion unit.

In an alternate embodiment, the water jacket and jet propulsion unit areformed as one integral piece as is well known in the art. In thisembodiment, a channel is formed between the jet propulsion component andwater jacket, as in the embodiment already described, by providing amold that produces such a channel.

The jacket, formed according to any of the embodiments, includes aninlet (not shown) for coupling the oil reservoir to the cooling jacketto deliver heated oil to the cooling jacket and an outlet (not shown)for returning the cooled oil to the oil reservoir 33. The inlet andoutlet may be formed as orifices for receiving oil passage lines asshown in FIG. 3 in a sealed manner so that no oil is lost in the coolingprocess.

The cooling channel, according to any embodiment, is sized and shaped sothat it interfaces with the component of the jet propulsion unit withoutinterfering with the operation of the jet propulsion unit. For example,if the cooling channel is provided on the second nozzle (shown in FIG.2), it should be of a size and configuration so as to not interfere withthe pivotal rotation of the rotatable nozzle (shown in FIG. 2).

The channel may be provided on any component of the jet propulsion unitthat is between the inlet and outlet of the jet pump. For example,without limitation, the channel may be provided on the pump extension,the jet pump housing, the stator, the first stationary nozzle or thesecond rotatable nozzle (all shown in FIG. 2). The only requirements forthe placement of the cooling channel is that it lie adjacent to the flowof water through the jet propulsion unit and the component is of a sizeso that a sufficient surface is exposed to the water flowing through thejet propulsion unit to accomplish adequate cooling of the oil.

The cooling system can be used to cool any number of engine fluids. AsFIG. 3 illustrates diagrammatically, the cooling system may be used tocool the engine cooling fluid. As depicted, coolant from the closed loopcooling system 57 may be directed to the open loop cooling system 59 andheat contained within the engine fluid is transferred to the waterflowing through the jet propulsion unit 40 as described above.

The engine fluid cooling process is illustrated diagrammatically in FIG.8. As the engine operates, various engine fluids, including lubricatingoil and coolant, are circulated through various engine parts. Duringcirculation, the temperature of the engine fluids increases. To functioneffectively, these fluids must be cooled before subsequent cyclingthrough system. Contemporaneously with fluid cycling, the engine drivesa drive shaft that rotates an impeller. As the impeller rotates, wateris drawn inward and flows through the jet propulsion unit. Heated enginefluids are transferred to the jet propulsion unit where a heat transferbetween the engine fluid and the ambient water entering the jetpropulsion unit occurs. Finally, the cooled engine fluid is routed backto the engine where it can be cycled again.

Thus, embodiments of the Personal Watercraft Engine Fluid Cooling Systemare disclosed. One skilled in the art will appreciate that theseembodiments can be practiced with embodiments other than thosedisclosed. The disclosed embodiments are presented for purposes ofillustration and not limitation, and the embodiments are limited only bythe claims that follow.

1. A system for a personal watercraft having an engine fluid coolingapparatus, the system comprising: a hull and an overlying deck, forminga cavity that defines an engine compartment; an engine, located in theengine compartment, coupled to a jet propulsion unit for powering thewatercraft; and an engine fluid passage surrounding a component of thejet propulsion unit for directing the engine fluid through the enginefluid passage so that heat in the engine fluid is transferred to watertaken up by the jet propulsion unit.
 2. The personal watercraft of claim1, further including an engine fluid channel line coupling an enginefluid reservoir to the engine fluid passage for delivering heatedlubricating fluid to the passage for cooling.
 3. The personal watercraftof claim 1, wherein the engine fluid passage is a conduit coiled aboutthe component of the jet propulsion unit.
 4. The personal watercraft ofclaim 1, wherein the engine fluid passage is a coil formed about a jetpump housing of the jet propulsion unit.
 5. The personal watercraft ofclaim 1, wherein the engine fluid passage is a channel formed between anexterior of the component of the jet propulsion unit and a jacket formedabout the component of the jet propulsion unit.
 6. The personalwatercraft of claim 5, wherein the jacket is integral with the componentof the jet propulsion unit.
 7. The personal watercraft of claim 1,wherein the engine fluid passage is a channel formed between an exteriorof a jet pump housing of the jet propulsion unit and a jacket formedthereabout.
 8. An engine fluid cooling apparatus for a jet-propelledwatercraft, comprising: an engine fluid passage formed about a componentof a jet propulsion unit for circulating engine fluid thereabout, and anengine fluid passageway coupling an engine fluid reservoir to the enginefluid passage, wherein heated engine fluid is delivered to the enginefluid passage where it is cooled and then returned to the engine fluidreservoir.
 9. The cooling system of claim 8, wherein the engine fluidpassage is formed by coiling a hollow conduit about the component of thejet propulsion unit.
 10. The cooling system of claim 8, wherein theengine fluid passage is a hollow conduit coiled about a stator of thejet propulsion unit.
 11. The cooling system of claim 8, wherein theengine fluid passage is formed by coiling a hollow conduit coiled abouta jet pump housing of the jet propulsion unit.
 12. The cooling system ofclaim 8, wherein the engine fluid passage is a channel formed between anexterior of the component of the jet propulsion unit and a jacket thatat least partially surrounds the component of the jet propulsion unit.13. The cooling system of claim 12, wherein the component of the jetpropulsion unit is a stator.
 14. The cooling system of claim 12, whereinthe component of the jet propulsion unit is a jet pump housing.
 15. Ajet propulsion unit for a jet-propelled watercraft, comprising: an outerhousing; an impeller journalled within the outer housing; a dischargenozzle positioned rearward of the impeller; and an engine lubricatingfluid channel formed contiguously with the outer housing so that heatfrom an engine fluid is transferred to water flowing through the jetpropulsion unit.
 16. The jet propulsion unit of claim 15, wherein theengine lubricating fluid channel is couplable to an engine lubricatingfluid reservoir.
 17. The jet propulsion unit of claim 15, wherein theengine lubricating fluid channel is a hollow conduit coiled around theouter housing.
 18. The jet propulsion unit of claim 17, wherein thehollow conduit is coiled around a jet pump housing.
 19. The jetpropulsion unit of claim 17, wherein the hollow conduit is coiled arounda stator of the jet propulsion unit.
 20. The jet propulsion unit ofclaim 15, further comprising an inlet in the engine lubricating fluidchannel for receiving heated lubricating fluid from an engine of thewatercraft.
 21. The jet propulsion unit of claim 20, further comprisingan outlet in the engine lubricating fluid channel for diverting cooledlubricating fluid back to the engine.
 22. A cooling system for coolingan engine fluid of a watercraft, comprising: cooling means formed abouta component of the jet propulsion unit; and means for transporting theengine fluid to and from the cooling means.
 23. A method of cooling anengine fluid of a watercraft, the method comprising the steps of:diverting an engine fluid from a circulatory path to an engine fluidcooling system located at a jet propulsion unit of a watercraft;transferring heat stored in the engine fluid to ambient water travelingthrough the jet propulsion unit thereby cooling the engine fluid; andreturning the cooled engine fluid to its circulatory path.
 24. A methodof cooling an engine fluid in a watercraft, comprising the step of:circulating a heated engine fluid adjacent to a component of a jetpropulsion unit so that heat contained in the engine fluid istransferred to ambient water flowing through the jet propulsion unit.